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Aviation History
1948
1948 - 0368.PDF
FLIGHT MARCH IHTH, 1948 TY.,^1* possible on the fuel capacity of jo U.S. gall., which, inci-UUCK . . • dentally, is provided by a nylon tank. We alighted on the Medway both at Shorts and farther board end of the facia. The throttle is centrally placed downstream, and have to record nothing short of astonishment between the inverted spectacle wheels for aileron and elevator at the well-nigh incredible way in which the Duck can be control, these protruding through the trailing edge of a tray motored around on the water. Certainly, it is unlikely that furnished with recessed ashtrays and a clip for maps. A small one would ever need to perform such evolutions, but for the sphere-compass is mounted above the - purposes of demonstration, we skittered instrument ,)anel in the centre of the J>^ round at about 30 knots and made tight front screen. A '"^xH sodding turns of certainly no more than Access to the cabin is afforded by a 1 100ft radius with the boat up on the wide dooi to starboard, whilst the side M ,' /V steP and heeling inward like an M.T.B. window glazing curves overhead to a 9 ,\y^__\ Yet tne inside float only trailed its heel central ridge, and has the roof portion jB // lightly over the water. Jyed blue for glare protection. The Wm * ' F°r more normal marine work, a water front screen, although curved and set jB rudder is housed inside the base of the well forward, does provide a remarkable S 1 udder proper, and can be let down by field of view, which is emphasized by the B releasing a cord in the cabin roof. H normal slightly nose-down cruising atti- m&mmmmmimimmz ever' the Duck can be handled q tude of the aircraft. mg^^^^^^mg^j^^ effectively on the water without using Flying the Duck was a pleasant ex- "JiS^aHfc ^^?. this refinement. Take-off and toucb- perience. Take-off is quick, and at a JSOSS down are both equally simple, no matter recommended climbing speed of 75 IJEsaBo' , whether land or water is the surface, and I.A.S.. the rate of climb is something HB^^^^^fclsfc. there is no doubt in our minds that this over i,oooft/min. Probably due to the VH|^^^^p" little aircraft well deserves a place in the unobstructed slipstream from the pusher BSrT^RKiw^ sun' ** *s a^ *^e more unfortunate that airscrew, the rudder is both light and SB W ™"P^^ tne American Goodyear company have powerful, although it must be said that ^B I\ \ \S decided not to build any more than the it does harmonize well with the other ffflf 1^ 11 * existing fifteen, although, of course, it two controls. At the normal cruising B» \\ 11 \ is open for any other manufacturer to figure ot 2,450 r.p.m., the Duck flies ^H ll I s undertake construction under licence. It along at 115 m.p.h., I.A.S., and in these BF II 1 I is estimated that, if two thousand Duck* conditions, the noise level in the cabin f Hi 1 ».. ~x could be sold, they could be marketed at is relatively low ; it is not, however, so t0&tm itil\ ^ * ' a price of about $7,000.quiet as one would expect with an engine JJP$HBHHBBS COODVEAR our and airscrew positioned as applies here. ^^^^^W^^^J^-^ COODTEAR DUCK The stall is gentle and straightforward **"- ^ — wing»rea " " liss'ft at about 55 m.p.h. I.A.S., and the built- Length "... "... '.'.'. '.'.'. "'. 27ft Oin in leading-edge slots not only ensure The Franklin flat-six engine is air cooled Height 11 ft 6in effective lateral control at the stall but with the aid of an extractor fan and Underan-iaee track 9fc0i!! also make the pre-stall attitude quite drives an automatically variable-pitch Wheeibase :.. ... ... .'.'. ... I5ft6in steep A range of about 300 miles is Aeromatic propeller. ^^^^^^Z^^^^ZL^^^L^^^^^. Rotol Turbine Airscrew* THE airscrew side of airscrew-turbine combinations hasnot received so much general notice as the power-sourceside; it is, nevertheless, a subject which is of consider- able interest Rotol, Ltd., have announced the d6but of three airscrews designed for turbines of the Mamba, Dart and Naiad class. These three airscrews are, respectively, a 3-blade constant- speed and feathering unit, a 3-blade constant-speed and braking type, and a 4-blade constant-speed feathering and braking unit All ace suitable for No 4 S.B.A.C. shafts, J^ have a common diameter of ten feet and employ solid Duralumin blades of " paddle-type " plan form. The chord of each blade is 12.35m, and the activity factor is 127.5. (Activity factor is a non-dimensional quantity which is an index of the power absorption of the blade.) Weights are respectively 240 lb, 243 lb and 275 lb, these being for the bare airscrews without spinners. Starting a gas turbine in- volves overcoming the rela- tively high inertia inherent in such a system, and build- ing-up sufficient r.p.m. for the compressor to deliver enough air to support com- bustion. Having to over- come, in addition, the drag occasioned by rotating an airscrew imposes a load- increase on +he starter which The new Rotol four-blade c.s. feathering and braking air- screw fitted with ducted spinner, as designed for installation with the Armstrong Siddeley Mamba. reduced to a minimum, and the only additional load placed on the starter by the airscrew is that of inertia. The airscrews are fitted with mechanical safety locks for flight to ensure that, in the event of engine or airscrew-control system failure, the blades will not move beyond normal fine pitch into the neutral thrust position. The system of control is vested in a con- troller unit, which combines constant-speed and braking units, giving constant speeding down to zero pitch and through to negative pitch for reverse-thrust braking. In conjunction with this development has been coincident work on ducted spinners. A description of the Napier duct*^.- spinner was published in Flight, October 3rd, 1946, and \f descendant of this is now being built by Rotols for the Napier Naiad Ducted spinners are also in hand for the Rolls-Royce Dart, and we illustrate such a component fitted to the Rotol 4-blade c.s. feathering and braking airscrew designed for the Armstrong Siddeley Mamba. '* In our issues of August 7th and 14th, 1947, we published an article on Air- screws for Gas Turbines by Mr. L. G. Fairhunst, chief engineer of Rotol, Ltd., in which the problems were fully discussed and possible solutions suggested. is unacceptable. To ob- viate this, the new Rotol airscrews incorporate provision for the blades to be turned to zero pitch, so that aerodynamic drag is A FRENCH HISTORY THE second volume of Vingl-Cinq Annies d'Aviation Mili-taire, by General J. Hebrard, has now been issued (price 750 francs) by Editions Albin Michel, Paris. This section of a work which has already covered, in Volume I, the period 1920-1939, deals with the Air War of 1939-1945. "RECORDS FEMININ" MISS MARY WILKINS has written us in connection withour suggestion that women should be given the oppor- tunity to raise the existing world's speed record of 292 m.p.h. During her service in A.T.A. she has flown faster than this, has 1100 hours' flying on 56 types of aircraft, including a Gloster Meteor, and offers her services in any proposed attempt to raise the record. Pier address is The Manor House, Brize- Norton, Oxford (Telephone Carterton 228).
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